When the idea of selling carbon offsets by otherwise profitable businesses is described twice in the same month as “gravy,” you know offsets have an image problem.

Are offsets just hot air, or necessary evil? (AP)

But the bigger question remains. Is the market for carbon offsets, imperfect as it is, a necessary evil if real progress is to be made cutting emissions of greenhouse gases?

Our colleague Jeff Ball reports today in the WSJ on the latest blow to the credibility of the offset market, that is, when companies get paid for cutting greenhouse-gas emissions. Landfills have been capturing methane for years, and making money off it–but thanks to the growing offset market, they are getting paid twice. As the paper says:

The sale of credits by these landfills undermines a premise of the global fight against climate change. The credit system was designed to encourage pollution cuts that wouldn’t have happened without a financial incentive. But the credits aren’t helping the environment if they’re merely providing extra profit for cleanups already made. And dumps already have an incentive to capture methane because selling it can be profitable.

This is what has many environmentalists troubled. Projects that rake in cash, be they landfills or Mongolian wind farms, are supposed to provide real, not bogus, emissions cuts. When rich countries and rich companies turn to the offset market to clean up their act, they aren’t really cleaning up the environment at all, many argue.